Camera body, lens barrel and lens-interchangeable camera

ABSTRACT

A camera body includes a body-side bayonet lug, wherein a lens-side bayonet lug of a lens barrel is positioned immediately behind the body-side bayonet lug when the lens barrel is mounted to the camera body; an opposed surface formed on the rear surface of the body-side bayonet lug and positioned immediately in front of the lens-side bayonet lug; a body-side mount surface positioned in front of the opposed surface and with which the lens-side bayonet surface comes into contact; and a body-side contact portion, the front end of which contacts the rear end of the lens-side contact portion when the opposed surface faces the lens-side bayonet lug, the front end of the body-side contact portion being positioned in front of the opposed surface and behind the body-side mount surface.

TECHNICAL FIELD

The present invention relates to a camera body, a lens barrel and alens-interchangeable camera.

BACKGROUND ART

Lens-interchangeable cameras which include a camera body and a lensbarrel which can be attached and detached to and from a substantiallycircular opening formed on the front of the camera body are known in theart (e.g., Patent Literatures 1 and 2).

This type of camera body is provided with a plurality of (e.g., three)body-side bayonet lugs which project from the edge of the opening towardthe inner peripheral side, and body-side contact portions which areconnected to a battery and a controller, etc., that are installed in thecamera body. On the other hand, the lens barrel is provided with aplurality of (e.g., three) lens-side bayonet lugs which project towardthe outer peripheral side and lens-side contact portions which areconnected to a lens drive motor and other which are installed in thelens barrel.

Upon the lens barrel being mounted to the camera body using thebody-side bayonet lugs and the lens-side bayonet lugs, the body-sidecontact portions and the lens-side contact portions come into contactwith each other to establish electrical continuity and conductivity,which allows the lens drive motor, etc., to operate using power of thebattery installed in the camera body.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No.2010-44203

Patent Literature 2: Japanese Unexamined Patent Publication No.2010-117571

SUMMARY OF THE INVENTION Technical Problem

When the camera body and the lens barrel are disengaged from each other,the body-side contact portions and the lens-side contact portions areoutwardly exposed. If the platings on the surfaces of the body-sidecontact portions and the lens-side contact portions are damaged by thetouching of the hands, etc., of the user on the body-side contactportions and the lens-side contact portions thus exposed, the conductioncapabilities of the body-side contact portions and the lens-side contactportions deteriorate. Accordingly, to make it difficult for the hands,etc., of the user to touch the body-side contact portions in thedisengaged state, the body-side contact portions are arranged, e.g.,behind the body-side mount surface (on the side closer to the imagepickup device in the lens optical axis direction). On the other hand, inorder to be connected with the aforementioned body-side contactportions, the lens-side contact portions are provided at a position thatprojects from the position of the lens-side bayonet lugs in the lensoptical axis direction. Therefore, unlike the body-side contactportions, the lens-side contact portions easily damage by a user's touchor easily damage by colliding with the camera-body-side mount surfacewhen the lens barrel is mounted to the camera body.

Additionally, in recent years, so-called mirrorless interchangeable-lenscameras, in which a viewfinder optical system is omitted to slim thecamera (to reduce the size thereof in the optical axis direction) havebeen available on the market. However, in the case of mirrorlessinterchangeable-lens cameras, the distance (flange back distance) fromthe body-side mount surface to the imaging surface of the image pickupdevice is designed short, so that there is no alternative but for thebody-side contact portions to be disposed in the vicinity of the mountsurface; moreover, the position of the light receiving surface of theimage pickup device is also close to the mount surface, and accordingly,a new contrivance to improve this structure is desired.

The present invention provides a camera body, a lens barrel and alens-interchangeable camera, wherein the body-side contact portion (s)and the lens-side contact portion (s) can be protected when the camerabody and the lens barrel are disengaged from each other while achievingminiaturization of the camera in the optical axis direction.

Solution to Problem

A camera body according to the present invention is characterized byhaving a substantially circular opening formed in a front side thereof,a lens barrel being capable of being attached and detached to and fromthe opening, wherein the lens barrel includes a lens-side bayonet lugwhich is provided at a rear end of the lens barrel and projects towardan outer peripheral side, a lens-side contact portion, a rear end ofwhich is exposed, and a lens-side mount surface, and wherein the camerabody includes a body-side bayonet lug which projects from a peripheraledge of the opening toward an inner peripheral side, wherein thelens-side bayonet lug is positioned immediately behind the body-sidebayonet lug when the lens barrel is mounted to the camera body; anopposed surface which is formed on a rear surface of the body-sidebayonet lug and is positioned immediately in front of the lens-sidebayonet lug when the lens barrel is mounted to the camera body; abody-side mount surface which is positioned in front of the opposedsurface and with which the lens-side bayonet surface comes into contactfrom front when the opposed surface faces the lens-side bayonet lug; anda body-side contact portion, a front end of which comes into contactwith the rear end of the lens-side contact portion when the opposedsurface faces the lens-side bayonet lug, the front end being positionedin front of the opposed surface and behind the body-side mount surface.

The lens-side bayonet lug and the body-side bayonet lug can beconcentrically circular-arcular in shape, wherein the camera bodyincludes a circular arc protrusion which is projected forward inside thecamera body, spaced from the body-side bayonet lug toward the innerperipheral side and concentric with the body-side bayonet lug, andwherein the body-side contact portion is provided on a front end surfaceof the circular arc protrusion.

In such a case, the body-side contact portion can be held in thecircular arc protrusion to be capable of advancing and retracting, andthe camera body can include a contact biaser which is provided in thecircular arc protrusion to bias and move the body-side contact portionforward.

The circular arc protrusion can protrude to a position substantiallyidentical to a position of the body-side bayonet lug in a directionorthogonal to the body-side mount surface.

A portion of a light receiving area of an image pickup device can bepositioned in the vicinity of an inner peripheral side of the circulararc protrusion.

A lens barrel, capable of being attached and detached to and from asubstantially circular opening formed on front of a camera body,according to the present invention is characterized by including abody-side bayonet lug which is provided on a peripheral edge of theopening and projects toward an inner peripheral side, an opposed surfacewhich is formed on a rear surface of the body-side bayonet lug, abody-side mount surface, a body-side contact portion, a front end ofwhich is positioned in front of the opposed surface and behind thebody-side mount surface, wherein the lens barrel includes a lens-sidebayonet lug which projects toward an outer peripheral side from a rearend thereof and is positioned immediately behind the opposed surface ofthe body-side bayonet lug when the lens barrel is mounted to the camerabody; a lens-side mount surface which comes into contact with thebody-side bayonet surface from a front side when the lens-side bayonetlug faces the opposed surface; a recessed groove which is circular arcor annular in shape, formed on a rear surface of the lens barrel andpositioned on an inner peripheral side of the lens-side bayonet lug; anda lens-side contact portion, a rear end of which is positioned in therecessed groove, wherein the rear end of the lens-side contact portioncomes into contact with the front end of the body-side contact portionwhen the opposed surface faces the lens-side bayonet lug.

A lens-interchangeable camera according to the present invention ischaracterized by including a camera body which includes a body-sidebayonet lug which is provided on a peripheral edge of an opening formedon front of the camera body and projects toward an inner peripheralside, an opposed surface which is formed on a rear surface of thebody-side bayonet lug, a body-side mount surface, and a body-sidecontact portion, a front end of which is positioned in front of theopposed surface and behind the body-side mount surface; and a lensbarrel which includes a lens-side bayonet lug which projects toward anouter peripheral side from a rear end thereof and is positionedimmediately behind the opposed surface of the body-side bayonet lug whenthe lens barrel is mounted to the camera body, a lens-side mount surfacewhich comes into contact with the body-side bayonet surface from frontwhen the lens-side bayonet lug faces the opposed surface, a recessedgroove which is circular arc or annular in shape, formed on a rearsurface of the lens barrel and positioned on an inner peripheral side ofthe lens-side bayonet lug, and a lens-side contact portion, a rear endof which is positioned in the recessed groove, wherein the rear end ofthe lens-side contact portion comes into contact with the front end ofthe body-side contact portion when the opposed surface faces thelens-side bayonet lug.

The camera body can include a circular arc protrusion inside the camerabody, the circular arc protrusion projecting forward, being spaced fromthe body-side bayonet lug toward the inner peripheral side, and beingconcentric with the body-side bayonet lug, wherein the body-side contactportion is provided on a front end surface of the circular arcprotrusion, and the circular arc protrusion and the body-side contactportion are positioned in the recessed grove when the lens barrel ismounted to the camera body.

Advantageous Effects of the Invention

The camera body according to the present invention makes it possible toreduce the possibility of the hands, etc., of the user touching thebody-side contact portion when the camera body and the lens barrel aredisengaged from each other because the front end of the body-sidecontact portion is positioned in front of the opposed surface of thebody-side bayonet lug, which constitutes the rear surface thereof, andbehind the body-side mount surface.

In addition, since the lens-side contact portion is positioned in therecessed groove of the lens barrel, the lens barrel can reduce thepossibility of the hands, etc., of the user touching the lens-sidecontact portion when the camera body and the lens barrel are disengagedfrom each other.

Additionally, if the front end of the body-side contact portion ispositioned behind the aforementioned opposed surface, the size of thewhole camera body in the optical axis direction increases because aspace for accommodating a battery and a controller, etc., needs to beformed in a portion of the internal space of the camera body which ispositioned behind the body-side contact portion. However, since thefront end of the body-side contact portion is positioned in front of theaforementioned opposed surface, the size of the whole camera body in theoptical axis direction can be reduced.

Additionally, since the recessed groove that receives the body-sidecontact portion when the lens barrel is connected to the camera body isformed in a rear surface of the lens barrel, the size of the wholecamera body in the optical axis direction when the camera body and thelens barrel are connected can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is front perspective view of an embodiment of a camera accordingto the present invention.

FIG. 2 is a front perspective view of the camera body.

FIG. 3 is a front elevational view of the camera body.

FIG. 4 is a rear perspective view of the lens barrel, wherein the barrelbody thereof is abbreviated.

FIG. 5 is a rear elevational view of the lens barrel, wherein the barrelbody thereof is abbreviated.

FIG. 6 is a side elevational view of the lens barrel, illustrating onlyan upper half thereof as a cross section taken along the line VI-VIshown in FIG. 5, wherein the barrel body is shown by an imaginary line.and

FIG. 7 is a longitudinal sectional view of a central portion of thecamera taken along the line VII-VII shown in FIG. 1, wherein the barrelbody and the external casing are schematically simplified and shown byimaginary lines.

DESCRIPTION OF EMBODIMENT

An embodiment according to the present invention will be hereinafterdiscussed with reference to the attached drawings. Forward and rearwarddirections, leftward and rightward directions, and upward and downwarddirections that are described in the following description are definedbased on the directions of arrows shown in the drawings.

As shown in the drawings, the present embodiment of the camera 10 isprovided with a camera body 20 and a lens barrel 50 which can beattached and detached to and from each other.

The camera body 20 is provided with a hollow external casing 21. Aplurality of operating buttons are provided on the upper and frontsurfaces of the external casing 21, and an LCD is provided on the backof the external casing 21. A circular opening hole 22 is formed in acentral portion of the front of the external casing 21, and a body-sidemount ring 23 made of metal which has a substantially ring shape isfitted into the opening hole 22 and fixed thereto. The inner peripheralside portion of the front of the body-side mount ring 23 is formed as abody-side mount surface 24 which projects a step forward from theposition of the outer peripheral side portion of the front of thebody-side mount ring 23. The body-side mount ring 23 is provided, on theedge of the opening thereof at positions a step rearward from theposition of the body-side mount surface 24, with body-side bayonet lugs25, 26 and 27 which are integrally formed to project toward the innerperipheral side. The body-side bayonet lugs 25, 26 and 27 are circulararc in shape about the center axis of the opening hole 22 (the opticalaxis of the lens barrel 50 when the lens barrel 50 is connected; an axisorthogonal to the body-side mount surface 24) and are provided atsubstantially equi-angular intervals in a circumferential directionabout this center axis. The body-side bayonet lug 26 is greater inlength (circumferential length) than the body-side bayonet lug 27, andthe body-side bayonet lug 25 is even greater in length than thebody-side bayonet lug 26. Additionally, body-side circular-arc openings28, 29 and 30, each of which is circular arc in shape about theaforementioned center axis, are formed between the adjacent body-sidebayonet lugs 25, 26 and 27. As shown in the drawings, the body-sidecircular-arc opening 29, which is formed between the body-side bayonetlugs 25 and 27, is greater in length (circumferential length) than thebody-side circular-arc opening 30, which is formed between the body-sidebayonet lugs 25 and 26, and the body-side circular-arc opening 28, whichis formed between the body-side bayonet lugs 26 and 27, is even greaterin length than the body-side circular-arc opening 29. As shown in FIGS.3 and 7, biasing springs S1, S2 and S3 (rearward biasers) which eachproduce a rearward biasing force by being resiliently deformed forwardlyare arranged at equi-angular intervals of 120 degrees in thecircumferential direction of the mount surface and installed onto therear surfaces of the body-side bayonet lugs 25, 26 and 27, respectively.Additionally, a protrusion 32 which is positioned at a middle positionbetween the body-side bayonet lugs 26 and 27 (i.e., at acircumferentially middle position of the body-side circular-arc opening28) and shorter in length (circumferential length) than the body-sidebayonet lug 27 is integrally projected from the edge of the opening ofthe body-side mount ring 23 at the same position as the body-sidebayonet lugs 25, 26 and 27 with respect to the forward/rearwarddirection. No biasing spring corresponding to the biasing spring S1, S2or S3 is installed onto the rear surface of the protrusion 32. Thedistance (circumferential length) between the protrusion 32 and thebody-side bayonet lug 26 and the distance (circumferential length)between the protrusion 32 and the body-side bayonet lug 27 are eachsmaller than the circumferential length of a lens-side bayonet lug 57which will be discussed later.

A lock pin 34 which extends in the forward/rearward direction isinstalled in a circular hole which is formed in the body-side mountsurface 24 in the vicinity of the lower end thereof. The lock pin 34 isfreely slidable in the forward/rearward direction between a lockedposition, to project forward from the body-side mount surface 24, and anunlocked position, to be fully accommodated in the circular hole, andthe lock pin 34 is biased to move toward the locked position by theforward biasing force of a biaser installed in the circular hole. Inaddition, a lock release button 35 is installed in a hole formed on thefront of the external casing 21. The lock release button 35 is freelyslidable between a non-operating position, to project forward from thefront of the external casing 21, and an operating position, to be fullyaccommodated in the hole, and the lock release button 35 is biased tomove toward the non-operating position by the forward biasing force of abiaser installed in the hole. When the lock release button 35 is in thenon-operating position (when the lock release button 35 is not pressedrearward), the lock pin 34 is in the locked position. When the lockrelease button 35 is in the operating position (when the lock releasebutton 35 is pressed rearward), the lock pin 34 moves to the unlockedposition against the biasing force of the aforementioned biaser.

In the internal space of the external casing 21, an intermediate supportplate 37 made of synthetic resin which has a substantially disk shapeorthogonal to the aforementioned center axis is installed. The entiresurface of the intermediate support plate 37 (which includes a circulararc protrusion 39 which will be discussed later) is black in color, anda surface-texturing process has been performed on this entire surface.As shown in FIG. 7, the outer edge of the intermediate support plate 37is fixed to the outer edge of the rear of the body-side mount ring 23,and a central rectangular aperture 38, in the shape of a rectangle, isformed in a central part of the intermediate support plate 37.

The circular arc protrusion 39, which is positioned immediately abovethe central rectangular aperture 38 and is centered about theaforementioned center axis, is integrally projected forward from thefront of the intermediate support plate 37. Since the opening hole 22(the body-side mount ring 23) is small in diameter, right and leftportions of the circular arc protrusion 39 face the body-side bayonetlugs 25 and 26 in radial directions of the opening hole 22 as viewedfrom front, respectively. In addition, a central portion of the circulararc protrusion 39 radially faces the body-side circular-arc opening 30.A plurality of pin support holes are formed in the front surface of thecircular arc protrusion 39 to be arranged at equal intervals, and metalcontact pins 40, 40 a, 41 and 41 a (body-side contact portions) areinstalled in the pin support holes. The front surface of the circulararc protrusion 39 projects forward to a position substantially identicalto the position of the body-side bayonet lug 26. The contact pins 40, 40a, 41 and 41 a are freely slidable between a projected position (seeFIGS. 2 and 3) to project greatly forward from the front of the circulararc protrusion 39 and a pressed position to be pressed rearward to befully embedded in the circular arc protrusion 39, and the contact pins40, 40 a, 41 and 41 a are biased to move toward the projected positionby forward biasing forces of compression coil springs 42 (see FIG. 7;contact biasers) which are installed in the pin support holes,respectively. As shown in FIG. 7, in a state where the lens barrel 50 ismounted to the camera body 20 (also in a state where the lens barrel 50is not mounted to the camera body 20), the front ends of the contactpins 40, 40 a, 41 and 41 a are positioned behind the body-side mountsurface 24 and in front of the rear surfaces (opposed surfaces) of thebody-side bayonet lugs 25, 26 and 27. The two contact pins 40 and 40 aat the far right are connected to a battery (not shown) which isinstalled in a rear space located behind the intermediate support plate37, and each contact pin 41 and 41 a is connected to a controller (notshown; which is equipped with a CPU, etc.) which is installed in theaforementioned rear space. As viewed from the front, the contact pin 40a at the far right and the biasing spring S1 lie on an extension line(see a one-dot chain line in FIG. 3) of a radial direction of thecircular arc protrusion 39, and the contact pin 41 a at the far left andthe biasing spring S2 lie on an extension line (see a one-dot chain linein FIG. 3) of a radial direction of the circular arc protrusion 39 asshown in FIG. 3.

An image pickup device 44 which is positioned immediately behind thecentral rectangular aperture 38 and immediately below the circular arcprotrusion 39 (in the vicinity of the inner periphery thereof), asviewed from the front, is installed in the aforementioned rear space ofthe external casing 21.

The lens barrel 50 is provided with a barrel body 51 having asubstantially cylindrical shape, and is provided in the barrel body 51with lens groups, a lens drive mechanism which moves the lens groupsforward and rearward in an optical axis direction, a motor which appliesa driving force to the lens drive mechanism, and a memory, etc., inwhich information on specifications (focal length information and thelike) of the lens barrel 50, all of which are not shown in the drawings.

A lens-side mount ring 52, made of metal, which is formed as a circularring-shaped member is fixed to the rear end surface of the barrel body51. The lens-side mount ring 52 is integrally provided with a fixed ringportion 53 which is fixed to the rear end surface of the barrel body 51and a rear surface of which forms a lens-side mount surface 53 a, acylindrical portion 54 which extends rearward from the fixed ringportion 53, and lens-side bayonet lugs 55, 56 and 57 which project fromthe rear end of the cylindrical portion 54 toward the outer peripheralside. The lens-side bayonet lugs 55, 56 and 57 are circular arc in shapeabout the optical axis of the aforementioned lens groups and formed toproject from the cylindrical portion 54 so as to be arranged atsubstantially equi-angular intervals about the optical axis. As shown inthe drawings, the lens-side bayonet lug 56 is greater in length(circumferential length) than the lens-side bayonet lug 57, and thelens-side bayonet lug 55 is even greater in length than the lens-sidebayonet lug 56. In addition, a recessed portion 58 having a circular arcshape is formed in the outer edge of the lens-side bayonet lug 55.Lens-side circular-arc openings 59, 60 and 61, each of which is circulararc in shape about the optical axis, are formed between the adjacentlens-side bayonet lugs 55, 56 and 57. As shown in the drawings, thelens-side circular-arc opening 60, which is formed between the lens-sidebayonet lugs 55 and 57, is greater in length (circumferential length)than the lens-side circular-arc opening 59, which is formed between thelens-side bayonet lugs 55 and 56, and the lens-side circular-arc opening61, which is formed between the lens-side bayonet lugs 56 and 57, isgreater in length than the lens-side circular-arc opening 60.

In addition, the lens-side bayonet lugs 55, 56 and 57 are provided onthe rear edges of the outer peripheral surfaces thereof with roundedsurfaces 55 a, 56 a and 57 a, respectively, each of which is chamferedinto a curved surface having a predetermined radius of curvature.

Additionally, the lens-side bayonet lugs 55, 56 and 57 and the recessedportion 58 correspond in circumferential length and shape to thebody-side circular-arc openings 28, 29 and 30 and the protrusion 32 onthe camera body 20 side, respectively; likewise, the body-side bayonetlugs 25, 26 and 27 and the protrusion 32 on the camera body 20 sidecorrespond in size and shape to the lens-side circular-arc openings 61,60 and 59 and the recessed portion 58 on the lens side, respectively.Accordingly, when the lens barrel 50 is mounted to the camera body 20,the lens-side bayonet lugs 55, 56 and 57 and the recessed portion 58 canenter to a point behind the rear surfaces of the body-side bayonet lugs25, 26 and 27 on the camera body 20 side through the body-sidecircular-arc openings 28, 29 and 30 and the protrusion 32 on the camerabody 20 side, respectively.

In addition, a lock hole 62 is formed in the lens-side mount surface 53a.

An insulating member 63 that is a ring-shaped member made of syntheticresin is fixed to the inner peripheral part of the rear surface of thefixed ring member 53.

Additionally, an inner cylindrical member 66 made of synthetic resin isfixed to the inner peripheral part of the rear surface of the insulatingmember 63. A circular hole 67 through which the aforementioned lensgroups are rearwardly exposed is formed in a center of the rear endsurface of the inner cylindrical member 66.

As shown in FIGS. 4, 5 and 7, a recessed groove 68 in the shape of acircular arc as viewed from rear is formed between the cylindricalportion 54 of the lens-side mount ring 52 and the inner cylindricalmember 66, and a plurality (the same number as the contact points 40, 40a, 41 and 41 a) of contacts 69 (lens-side contact portions), made ofmetal, are fixed to the rear of the insulating member 63, which formsthe bottom of the recessed groove 68, to be arranged at equi-angularintervals in a circumferential direction. The contacts 69 are connectedto the aforementioned motor and memory, etc.

Next, a manner of mounting the lens barrel 50 to the camera body 20 willbe discussed hereinafter.

First, the center axis of the opening hole 22 and the lens optical axisof the lens barrel 50 are brought into alignment with each other, andthe circumferential position of the recessed portion 58 is madecoincident with the protrusion 32; in this state, the rear end of thelens barrel 50 is brought close to the body-side mount ring 23 of thecamera body 20 from front, and subsequently, the lens-side bayonet lug55 is brought into the internal space of the external casing 21 throughthe body-side circular-arc opening 28. Subsequently, the lens-sidebayonet lug 56 is brought into the internal space of the external casing21 through the body-side circular-arc opening 29, and the lens-sidebayonet lug 57 is brought into the internal space of the external casing21 through the body-side circular-arc opening 30. Upon the lens-sidebayonet lug 55 being inserted into the body-side circular-arc opening28, the recessed portion 58 is loosely fitted on the protrusion 32 (therecessed portion 58 passes through the outside of the protrusion 32),and accordingly, the lens-side bayonet lug 55 enters the internal spaceof the external casing 21 without contacting the body-side bayonet lugs26 or 27, or the protrusion 32. Upon the lens-side bayonet lugs 55, 56and 57 being brought into the internal space of the external casing 21(brought to the rear of the body-side bayonet lugs 25, 26 and 27), thelens-side mount surface 53 a of the lens barrel 50 comes into contactwith the body-side mount surface 24 of the camera body 20 from front,and the lock pin 34 positioned in the locked position is pressed to theunlocked position by a portion of the lens-side mount surface 53 a (andsimultaneously, the lock release button 35 positioned in thenon-operating position moves to the operating position). In this state,rotating the entire lens barrel 50 clockwise by an angle ofapproximately 60 degrees, as viewed from the front, causes the lock hole62 to be positioned immediately in front of the lock pin 34, whichcauses the lock pin 34 held in the unlocked position by the lens-sidemount surface 53 a to move back to the locked position by the biasingforce of the aforementioned biaser (simultaneously causes the lockrelease button 35 in the operating position to move back to thenon-operating position by the biasing force of the aforementionedbiaser) to thereupon be engaged in the lock hole 62, which prevents thelens barrel 50 from further rotating. Additionally, as shown in FIG. 7,since a portion of the cylindrical portion 54 is positioned in arecess-shaped circular-arc space 45 between the circular arc protrusion39 and the body-side mount surface 24, when the lens barrel 50 rotates,the rotating operation of the lens barrel 50 is smoothly performed.Additionally, since the lens-side bayonet lugs 55, 56 and 57 arepositioned immediately behind the body-side bayonet lugs 26, 27 and 25while resiliently deforming the biasing springs S2, S3 and S1 forwardand since the lens-side bayonet lugs 55, 56 and 57 are pressed rearwardby the rearward biasing forces of the biasing springs S2, S3 and S1, thecontact state between the lens-side mount surface 53 a and the body-sidemount surface 24 is maintained. Accordingly, after the lens barrel 50 ismounted to the camera body 20 in this manner, the lens barrel 50 doesnot come off the camera body 20 unless the lock release button 35 isoperated. At this time, the protrusion 32 is located at a differentcircumferential position from the lens-side bayonet lugs 55, 56 and 57.

On the other hand, when the lens barrel 50 is mounted to the camera body20, the lens barrel 50 cannot be mounted to the camera body 20 if thecircumferential position of the recessed portion 58 is not madecoincident with the protrusion 32. For instance, in the case where thelens-side bayonet lug 57, the lens-side bayonet lug 56 and the lens-sidebayonet lug 55 are positioned at the same circumferential positions asthe body-side circular-arc opening 28, the body-side circular-arcopening 30 and the body-side circular-arc opening 29, respectively, thelens-side bayonet lugs 55, 56 and 57 cannot be inserted into theinternal space of the external casing 21 even if the axis of the lensbarrel 50 is made to be inclined with respect to the aforementionedcenter axis of the camera body 20 because the length (circumferentiallength) of the lens-side bayonet lug 57 is far greater than the distancebetween the protrusion 32 and the body-side bayonet lug 26 and thedistance between the protrusion 32 and the body-side bayonet lug 27, thelens-side bayonet lug 56 is greater in length than the body-sidecircular-arc opening 30 and the lens-side bayonet lug 55 is greater inlength than the body-side circular-arc opening 29. Likewise, also in thecase where the lens-side bayonet lug 55, the lens-side bayonet lug 56and the lens-side bayonet lug 57 are positioned at the samecircumferential positions as the body-side circular-arc opening 30, thebody-side circular-arc opening 28 and the body-side circular-arc opening29, respectively, the lens-side bayonet lugs 55, 56 and 57 cannot beinserted into the internal space of the external casing 21 even if theaxis of the lens barrel 50 is made to be inclined with respect to theaforementioned center axis of the camera body 20 because the lens-sidebayonet lug 55 is greater in length (circumferential length) than thebody-side circular-arc opening 30, the lens-side bayonet lug 57 isgreater in length than the body-side circular-arc opening 29, and thelength of the lens-side bayonet lug 56 is far greater than the distancebetween the protrusion 32 and the body-side bayonet lug 26 and thedistance between the protrusion 32 and the body-side bayonet lug 27.

Additionally, if the optical axis of the lens barrel 50 is inclined withrespect to the center axis of the opening hole 22 when the lens barrel50 is mounted to the camera body 20, the lens-side bayonet lug 55, 56 or57 attempts to enter the body-side circular-arc opening 30 in a slantingdirection. However, since this lens-side bayonet lugs 55, 56 or 57 is tocome into contact with a central portion of the circular arc protrusion39, the lens-side bayonet lugs 55, 56 and 57 are prevented from enteringthe inside of the camera body 20. Accordingly, the lens barrel 50 can bemounted to the camera body 20 only from a proper direction (i.e., from adirection substantially parallel to the optical axis).

Consequently, improper mounting, such as connecting the lens barrel 50to the camera body 20 without making the circumferential position of therecessed portion 58 coincident with the protrusion 32 and/or mountingthe lens barrel 50 to the camera body 20 with the lens barrel 50inclined to the camera body 20, can be prevented with reliability.

Upon the lens barrel 50 being mounted to the camera body 20, the contactpins 40, 40 a, 41 and 41 a of the camera body 20 are positioned in therecessed groove 68 of the lens barrel 50, and the rear end of eachcontact 69 of the lens barrel 50 comes in contact with the front end ofthe contact pin 40, 40 a, 41 or 41 a of the camera body 20 whilepressing the corresponding contact pin 40 or 41 from the projectedposition toward the pressed position. Therefore, upon a main switchprovided on the external casing 21 being turned ON, power of the batteryis supplied from the two contact pins 40 and 40 a to the correspondingcontacts 69, and the camera body 20 reads information stored in theaforementioned memory of the lens barrel 50 via the contacts pins 41 and41 a and the contacts 69.

When the lens barrel 50 is detached from the camera body 20, firstly thelock release button 35 in the non-operating position is manually pressedto the operating position to move the lock pin 34 that is in the lockedposition to the unlocked position to move the lock pin 34 out of thelock hole 62. Thereupon, the lens barrel 50 becomes rotatable relativeto the camera body 20, so that the recessed portion 58 is brought to aposition immediately behind the protrusion 32 by rotating the lensbarrel 50 counterclockwise by an angle of approximately 60 degrees asviewed from the front, and the entire lens barrel 50 is moved forwardwith respect to the camera body 20. Thereupon, the lens-side bayonet lug55 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 28, the lens-side bayonet lug56 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 29, and the lens-side bayonetlug 57 moves forward out of the internal space of the external casing 21through the body-side circular-arc opening 30, so that the lens barrel50 is disengaged from the camera body 20.

As described above, the present embodiment of the camera body 10, thelens barrel 50 and the camera body 20 can be reliably prevented frombeing improperly mounted to each other.

Moreover, the improper mounting prevention device according to thepresent invention has a simple structure configured of the protrusion 32and the circular arc protrusion 39, which are formed on the camera body20, and the recessed portion 58, which is formed on the lens barrel 50,thus not incurring a significant increase in cost, either.

In addition, since the front ends of the contact pins 40, 40 a, 41 and41 a are positioned behind the body-side mount surface 24 and in frontof the rear surfaces (opposed surfaces) of the body-side bayonet lugs25, 26 and 27, the possibility of the hands, etc., of the user touchingthe contact pins 40, 40 a, 41 and 41 a when the lens barrel 50 isdisengaged from the camera body 20 can be reduced.

Additionally, since the rounded surfaces 55 a, 56 a and 57 a areprovided on the lens-side bayonet lugs 55, 56 and 57, even if therounded surfaces 55 a, 56 a and 57 a are accidentally brought intocontact with the contact pins 40, 40 a, 41 and 41 a when the lens barrel50 is connected to the camera body 20, the contact pins 40, 40 a, 41 and41 a can be prevented from being scratched.

Additionally, since the lens barrel 50 is structured such that thecontacts 69 are positioned inside the recessed groove 68, thepossibility of the hands, etc., of the user touching the contacts 69when the lens barrel 50 is disengaged from the camera body 20 can bereduced.

Additionally, if the hands, etc., of the user touch the contact pins 40,40 a, 41 and 41 a when the lens barrel 50 is disengaged from the camerabody 20, the contact pins 40, 40 a, 41 and 41 a absorb the pressingforce transmitted from the hands, etc., of the user by moving completelyinside the pin support holes against the biasing forces of thecompression coil springs 42, the contact pins 40, 40 a, 41 and 41 a canbe prevented from being damaged. Additionally, the entire contact pins40, 40 a, 41 and 41 a are protected by the circular arc protrusion 39since the contact pins 40, 40 a, 41 and 41 a are positioned completelyinside the pin support holes.

Additionally, although the aforementioned rear space for accommodatingthe battery and controller, etc., is formed in part of the internalspace of the external casing 21 which is located behind the intermediatesupport plate 37, since the front ends of the contact pins 40, 40 a, 41and 41 a are positioned in front of the rear surfaces (opposed surfaces)of the body-side bayonet lugs 25, 26 and 27, the whole camera body 20can be reduced in dimensions in the optical axis direction (slimmeddown) (compared with the case where the front ends of the contact pins40, 40 a, 41 and 41 a are positioned behind the rear surfaces of thebody-side bayonet lugs 25, 26 and 27).

Additionally, since the recessed groove 68, which receives the circulararc protrusion 39 and the contact pins 40, 40 a, 41 and 41 a when thelens barrel 50 is connected to the camera body 20, is formed in the rearof the lens barrel 50, the camera 10 can be reduced in dimension in theoptical axis direction (slimmed down) (compared with the case where therecessed groove 68 that receives the contact pins 40, 40 a, 41 and 41 ais not formed on the lens barrel 50).

Additionally, when the lens barrel 50 is disengaged from the camera body20, a part (upper part) of the image pickup device 44 (the lightreceiving area of the imaging surface thereof) is positioned immediatelybelow the circular arc protrusion 39 (in the vicinity of the innerperipheral side of the circular arc protrusion 39) as viewed from front.Therefore, the circular arc protrusion 39 can prevent fingers of theuser or the like from accidentally touching the image pickup device 44(the light receiving area of the imaging surface thereof) or pressingthe image pickup device 44 (the light receiving area of the imagingsurface thereof).

Additionally, the front of the circular arc protrusion 39 protrudesforward to a position substantially identical to the positions of thebody-side bayonet lugs 25 and 26 in the thickness direction of thecamera body 20 (in a direction parallel to the center axis of theopening hole 22), and the body-side bayonet lugs 25 and 26 and the frontsurfaces of the circular arc protrusion 39 are substantially planar inarrangement (substantially lie in a plane), and accordingly, even whenone accidentally touches the bayonet lugs 25 and 26 or the periphery ofthe circular arc protrusion 39, the edges of the bayonet lugs 25 and 26can be prevented from hitting finger tips hard or finger tips can beprevented from being pinched between the edges of bayonet lugs 25 and 26and the circular arc protrusion 39, which makes it possible to achieve asafer mount structure.

When the lens barrel 50 is mounted to the camera body 20, the circulararc protrusion 39 and the recessed groove 68 have a nested structure inwhich the circular arc protrusion 39 is surrounded by the recessedgroove 68 (the cylindrical portion 54, the inner cylindrical member 66and the bottom of the recessed groove) as shown in FIG. 7. Accordingly,even if light outside the camera 10 enters inside the camera 10 betweenthe body-side mount surface 24 and the lens-side mount surface 53 a, thepossibility of this light reaching the inner peripheral side of thecircular arc protrusion 39 to thereby exert an adverse effect on thelight to be photographed which passes through the aforementioned lensgroups is small.

In addition, as viewed from the front, a portion of the lens-sidebayonet lug 57 lies on the same radial extension line as the contact pin40 a, and the biasing spring S1 biases this portion of the lens-sidebayonet lug 57 rearward. Additionally, as viewed from front, a portionof the lens-side bayonet lug 55 lies on the same radial extension lineas the contact pin 41 a, and the biasing spring S2 biases this portionof the lens-side bayonet lug 55 rearward. Accordingly, it is possible tomake the plurality of contact pins 40, 40 a, 41 and 41 a, which arearranged in a direction parallel to the circumferential direction of thebody-side mount ring 23, come into contact with the correspondingcontacts 69 securely with equal pressure.

Although the present invention has been described using the aboveillustrated embodiment, the present invention can be implemented withvarious modifications made to the above illustrated embodiment.

For instance, a configuration is possible in which theprojection-depression relationship between the protrusion 32 that isprovided on the camera body 20 side and the depression 58 that isprovided on the lens barrel 50 side is reversely applied to the lensbarrel 50 side and the camera body 20 side. In this case, a structure inwhich the above camera-body-side mount structure and lens-barrel-sidemount structure that have been described above are interchanged, namely,a modification is possible in which the lens-side mount ring 52 (thefixed ring portion 53) is provided with the protrusion 32 that isprovided on the body-side mount ring 23, and in which the body-sidemount ring 23 is provided with the recessed portion 58 that is providedon the lens-side mount ring 52.

Additionally, the number of the body-side bayonet lugs formed on thecamera body 20 and the number of the lens-side bayonet lugs formed onthe lens barrel 50 do not have to be three and can be any plural number(however, the number of the body-side bayonet lugs and the number of thelens-side bayonet lugs must be the same). Whatever the number of thebody-side bayonet lugs may be, a biasing spring is installed at the rearof each body-side bayonet lug, while no biasing spring is installed atthe rear of the protrusion 32.

Additionally, it is possible to make only some of the body-side bayonetlugs, only some of the circular-arc openings (which are positionedbetween the body-side bayonet lugs), only some of the lens-side bayonetlugs and only some of the circular-arc openings (which are positionedbetween the lens-side bayonet lugs) different in length from the otherthere of, or to make all the body-side bayonet lugs, all thecircular-arc openings (which are positioned between the body-sidebayonet lugs), all the lens-side bayonet lugs and all the circular-arcopenings (which are positioned between the lens-side bayonet lugs)mutually identical in length, rather than making all the body-sidebayonet lugs, all the circular-arc openings (which are positionedbetween the body-side bayonet lugs), all the lens-side bayonet lugs andall the circular-arc openings (which are positioned between thelens-side bayonet lugs) mutually different in length. However, in eachcase, the distance (circumferential length) between the protrusion 32and the body-side bayonet lug adjacent to the protrusion 32 is set to begreater than the length of the lens-side bayonet lug having the shortestlength.

Additionally, the recessed groove 68 can be made as an annular groovewhich is positioned between the cylindrical portion 54 of the lens-sidebayonet ring 52 and the inner cylindrical portion 66.

Additionally, the protrusion 32 can be provided in one of the circulararc grooves (among the circular arc grooves between the body-sidebayonet lugs) other than the circular arc groove that is the greatest inlength (e.g., can be provided in the circular arc groove which is thesmallest in length).

Additionally, the present embodiment of the camera 10 is a digitalcamera which is provided on the camera body 20 with the image pickupdevice 44; however, the present invention can also be applied to acamera using sliver-salt film.

INDUSTRIAL APPLICABILITY

The present invention has industrial applicability because the body-sidecontact portion(s) and the lens-side contact portion(s) can be protectedwhen the camera body and the lens barrel are disengaged from each otherwhile miniaturization of the camera in the optical axis direction isachieved.

REFERENCE SIGNS LIST

-   10 Camera-   20 Camera body-   21 External casing-   22 Opening hole-   23 Body-side mount ring-   24 Body-side mount surface-   25 26 27 Body-side bayonet lug-   28 29 30 Body-side circular-arc opening-   32 Protrusion-   34 Lock pin-   35 Lock release button-   37 Intermediate support plate-   38 Central rectangular aperture-   39 Circular arc protrusion-   40 41 Contact pin (body-side contact portion)-   42 Compression coil spring (contact biaser)-   44 Image pickup device-   50 Lens barrel-   51 Barrel body-   52 Lens-side mount ring-   53 Fixed ring portion-   53 a Lens-side mount surface-   54 Cylindrical portion-   55 56 57 Lens-side bayonet lug-   58 Recessed portion-   59 60 61 Lens-side circular-arc opening-   62 Lock hole-   63 Insulating member-   66 Inner cylindrical member-   67 Circular hole-   68 Recessed groove-   69 Contact (lens-side contact portion)-   S1 S2 S3 Biasing spring (rearward biaser)

The invention claimed is:
 1. A camera body having a substantiallycircular opening provided in a front side thereof, a lens barrel beingcapable of being attached and detached to and from said opening, whereinsaid lens barrel includes a lens-side bayonet lug which is provided at arear end of said lens barrel and projects toward an outer peripheralside, a lens-side contact portion, a rear end of which is exposed, and alens-side mount surface, and wherein said camera body comprises: abody-side bayonet lug which projects from a peripheral edge of saidopening toward an inner peripheral side, wherein said lens-side bayonetlug is positioned immediately behind said body-side bayonet lug whensaid lens barrel is mounted to said camera body; an opposed surfacewhich is provided on a rear surface of said body-side bayonet lug and ispositioned immediately in front of said lens-side bayonet lug when saidlens barrel is mounted to said camera body; a body-side mount surfacewhich is positioned in front of said opposed surface and with which saidlens-side bayonet surface comes into contact from front when saidopposed surface faces said lens-side bayonet lug; and a body-sidecontact portion, a front end of which comes into contact with said rearend of said lens-side contact portion when said opposed surface facessaid lens-side bayonet lug, said front end being positioned in front ofsaid opposed surface and behind said body-side mount surface and, whensaid lens barrel is attached to the camera body, the body side contactportion is positioned between the body side mount surface and theopposed surface.
 2. The camera body according to claim 1, wherein saidlens-side bayonet lug and said body-side bayonet lug are concentricallycircular-arcular in shape; wherein said camera body comprises a circulararc protrusion which is projected forward inside said camera body,spaced from said body-side bayonet lug toward said inner peripheral sideand concentric with said body-side bayonet lug, and wherein saidbody-side contact portion is provided on a front end surface of saidcircular arc protrusion.
 3. The camera body according to claim 2,wherein said body-side contact portion is held in said circular arcprotrusion to be capable of advancing and retracting, and wherein saidcamera body comprises a contact biaser which is provided in saidcircular arc protrusion to bias and move said body-side contact portionforward.
 4. The camera body according to claim 2, wherein said circulararc protrusion protrudes to a position substantially identical to aposition of said body-side bayonet lug in a direction orthogonal to saidbody-side mount surface.
 5. The camera body according to claim 2,wherein a portion of a light receiving area of an image pickup device ispositioned in the vicinity of an inner peripheral side of said circulararc protrusion.
 6. A lens barrel capable of being attached and detachedto and from a substantially circular opening provided on front of acamera body, wherein said camera body includes a body-side bayonet lugwhich is provided on a peripheral edge of said opening and projectstoward an inner peripheral side, an opposed surface which is formed on arear surface of said body-side bayonet lug, a body-side mount surface, abody-side contact portion, a front end of which is positioned in frontof said opposed surface and behind said body-side mount surface, whereinsaid lens barrel comprises: a lens-side bayonet lug which projectstoward an outer peripheral side from a rear end thereof and ispositioned immediately behind said opposed surface of said body-sidebayonet lug when said lens barrel is mounted to said camera body; alens-side mount surface which comes into contact with said body-sidebayonet surface from a front side when said lens-side bayonet lug facessaid opposed surface; a recessed groove which is circular arc or annularin shape, provided on a rear surface of said lens barrel and positionedon an inner peripheral side of said lens-side bayonet lug; and alens-side contact portion, a rear end of which is positioned in saidrecessed groove, wherein said rear end of said lens-side contact portioncomes into contact with said front end of said body-side contact portionwhen said opposed surface faces said lens-side bayonet lug, and when thelens barrel is attached to the camera body, the lens side contactportion is positioned between the lens side mount surface and theopposed surface.
 7. A lens-interchangeable camera comprising: a camerabody which includes a body-side bayonet lug which is provided on aperipheral edge of an opening formed on front of said camera body andprojects toward an inner peripheral side, an opposed surface which isformed on a rear surface of said body-side bayonet lug, a body-sidemount surface, and a body-side contact portion, a front end of which ispositioned in front of said opposed surface and behind said body-sidemount surface; and a lens barrel which includes a lens-side bayonet lugwhich projects toward an outer peripheral side from a rear end thereofand is positioned immediately behind said opposed surface of saidbody-side bayonet lug when said lens barrel is mounted to said camerabody, a lens-side mount surface which comes into contact with saidbody-side bayonet surface from front when said lens-side bayonet lugfaces said opposed surface, a recessed groove which is circular arc orannular in shape, provided on a rear surface of said lens barrel andpositioned on an inner peripheral side of said lens-side bayonet lug,and a lens-side contact portion, a rear end of which is positioned insaid recessed groove, wherein said rear end of said lens-side contactportion comes into contact with said front end of said body-side contactportion when said opposed surface faces said lens-side bayonet lug, andwhen said lens barrel is attached to the lens barrel the body sidecontact portion is positioned between the body side mount surface andthe opposed surface.
 8. The lens-interchangeable camera according toclaim 7, wherein said camera body comprises a circular arc protrusioninside said camera body, said circular arc protrusion projectingforward, being spaced from said body-side bayonet lug toward said innerperipheral side, and being concentric with said body-side bayonet lug,wherein said body-side contact portion is provided on a front endsurface of said circular arc protrusion, and wherein said circular arcprotrusion and said body-side contact portion are positioned in saidrecessed grove when said lens barrel is mounted to said camera body. 9.The lens-interchangeable camera according to claim 8, wherein saidcircular arc protrusion protrudes to a position substantially identicalto a position of said body-side bayonet lug in a direction orthogonal tosaid body-side mount surface.
 10. The lens-interchangeable cameraaccording to claim 7, wherein said lens-side bayonet lug and saidbody-side bayonet lug are concentrically circular-arcular in shape;wherein said camera body comprises a circular arc protrusion which isprojected forward inside said camera body, spaced from said body-sidebayonet lug toward said inner peripheral side and concentric with saidbody-side bayonet lug, and wherein said body-side contact portion isprovided on a front end surface of said circular arc protrusion.
 11. Thelens-interchangeable camera according to claim 10, wherein saidbody-side contact portion is held in said circular arc protrusion to becapable of advancing and retracting, and wherein said camera bodycomprises a contact biaser which is provided in said circular arcprotrusion to bias and move said body-side contact portion forward. 12.The lens-interchangeable camera according to claim 10, wherein saidcircular arc protrusion protrudes to a position substantially identicalto a position of said body-side bayonet lug in a direction orthogonal tosaid body-side mount surface.
 13. The lens-interchangeable cameraaccording to claim 10, wherein a portion of a light receiving area of animage pickup device is positioned in the vicinity of an inner peripheralside of said circular arc protrusion.
 14. The camera body according toclaim 1, further comprising a circular arc protrusion inside said camerabody, said circular arc protrusion projecting forward, being spaced fromsaid body-side bayonet lug toward said inner peripheral side, and beingconcentric with said body-side bayonet lug, wherein said body-sidecontact portion is provided on a front end surface of said circular arcprotrusion, and wherein said circular arc protrusion and said body-sidecontact portion are positioned in said recessed grove when said lensbarrel is mounted to said camera body.
 15. The camera body according toclaim 14, wherein said circular arc protrusion protrudes to a positionsubstantially identical to a position of said body-side bayonet lug in adirection orthogonal to said body-side mount surface.